Etorofu-class escort ship


The Etorofu-class escort ships were a group of fourteen kaibōkan escort vessels built for the Imperial Japanese Navy during World War II. Eight of the fourteen ships were sunk during the war. The class was also referred to by internal Japanese documents as the "Modified A-class" coastal defense vessel.

Background

The Shimushu-class kaibōkan, as with the torpedo boat, was a consequence of the 1930 London Naval Treaty, which placed limitations on the total destroyer tonnage the Imperial Japanese Navy was permitted. One way in which the treaty could be circumvented was to use a loophole in the treaty which permitted ships of between 600 and 2,000 tons, with no more than four guns over, no torpedoes, and with a maximum speed of no more than. A new class of vessel was designed to use this loophole, and was given the obsolete designation of kaibōkan, which had previously been used to designate obsolete battleships which had been reassigned to coastal defense duties. Immediately before the start of then Pacific War, the Imperial Japanese Navy suddenly decided to give more priority to convoy escorts, possibly in light of the ongoing successes of German U-boats against British shipping in the Atlantic. As the Shimushu class was not suited for mass-production and took too long to build, the 1941 Rapid Naval Armaments Supplement Programme authorized thirty modified versions of the Shimushu class, which were designated the Etorofu class. However, sixteen of the projected thirty ships were subsequently re-ordered to the subsequent Mikura, Hiburi or Ukura designs.
Production began between February 1942 and August 1943. Despite simplification, the design was still too complex for mass production and one of the ships was not completed until early 1944.

Description

The Etorofu class was almost identical to the Shimushu class but with a simplified bow, stern and bridge structure to facilitate production. The ships measured overall, with a beam of and a draft of. They displaced at standard load and at deep load. The ships had two diesel engines, each driving one propeller shaft, which were rated at a total of for a speed of. The ships had a range of at a speed of.
As with the Shimushu class the main battery of the Etorofu class consisted of three Type 3 guns in single mounts, one superfiring pair aft and one mount forward of the superstructure. Anti-aircraft protection was by four Type 96 anti-aircraft guns in two twin-gun mounts abreast the bridge. However, for a ship supposedly designed for convoy escort, only one Model 94 depth charge launcher was installed on the quarterdeck along with a Model 3 loading frame. The number of depth charges was initially 36, but this was increased to 60 while the ships were still in production, which necessitated the deletion of the two paravanes initially in the design for minesweeping. The ships were also equipped with a Model 93 sonar and a Type 93 hydrophone.
During the Pacific War, the number of Type 96 anti-aircraft gun was increased to five triple-mounts and a varying number of single-mounts, up to 15 in total by August 1943. A Type 22 and Type 13 radar were also installed. A Type 97 trench mortar was also installed front of the bridge

Operational service

The Etorofu class proved to be an inadequate design by the time the final units entered service in 1944. Their speed was slower than most submarines, and with only one depth charge projector, their combat capability against the increasingly effective United States Navy submarine forces was ineffective. The Etorofu-class vessels were mostly deployed to the South China Sea or East China Sea as convoy escorts, but few recorded any attacks against Allied submarines. Conversely, six of the 14 ships in the class were sunk by American submarines. Of the six survivors, three were used as repatriation ships after the war, and were subsequently given as prize of war to Allied navies.

Ships in class

Thirty ships were included in the Rapid Naval Armaments Supplement Programme in 1941. These are listed below with the shipyard to which each was allocated:
NumberNameBuilder
#310EtorofuHitachi-Sakurajima Shipyards
#311MatsuwaMitsui-Tamano Shipyards
#312SadoNKK-Tsurumi Shipyards
#313OkiUraga Dock Company
#314MatsureHitachi-Sakurajima Shipyards
#315IkiMitsui-Tamano Shipyards
#316TsushimaNKK-Tsurumi Shipyards
#317WakamiyaMitsui-Tamano Shipyards
#318HiradoHitachi-Sakurajima Shipyards
#319FukaeUraga Dock Company
#320MikuraNKK-Tsurumi Shipyards
#321AmakusaHitachi-Sakurajima Shipyards
#322MiyakeNKK-Tsurumi Shipyards
#323ManjuMitsui-Tamano Shipyards
#324AwajiHitachi-Sakurajima Shipyards

NumberNameBuilder
#325KanjuUraga Dock Company
#326NōmiHitachi-Sakurajima Shipyards
#327KurahashiNKK-Tsurumi Shipyards
#328HiburiHitachi-Sakurajima Shipyards
#329ChiburiNKK-Tsurumi Shipyards
#330KasadoUraga Dock Company
#331YashiroHitachi-Sakurajima Shipyards
#332UkuruNKK-Tsurumi Shipyards
#333DaitōHitachi-Sakurajima Shipyards
#334KusagakiNKK-Tsurumi Shipyards
#335OkinawaNKK-Tsurumi Shipyards
#336AmamiNKK-Tsurumi Shipyards
#337AguniNKK-Tsurumi Shipyards
#338ShinnanUraga Dock Company
#339ShōnanHitachi-Sakurajima Shipyards

While fourteen of the above ships were completed to the Etorofu design, eight ships - Mikura, Miyake, Awaji, Nōmi, Kurahashi, Chiburi, Yashiro and Kusagaki - were altered to be built to the Mikura design; three ships - Hiburi, Daitō and Shōnan - were altered to be built to the Hiburi design; and five ships - Ukuru, Okinawa, Amami, Aguni and Shinnan - were altered to be built to the 'Ukuru design. The fourteen completed to the Etorofu design were as follows:
KanjiNameBuilderLaid downLaunchedCompletedFate
択捉Hitachi-Sakurajima Shipyards23 February 194229 January 194315 May 1943Ceded to the United States, 1946. Scrapped 1947
松輪Mitsui-Tamano Shipyards20 April 194213 November 194223 March 1943Sunk by on 22 August 1944, Hidai Bay, Philippines
佐渡NKK-Tsurumi Shipyards21 February 194228 November 194227 March 1943Sunk by on 22 August 1944, Hidai Bay, Philippines
隠岐Uraga Dock Company27 February 194220 October 194228 March 1943Ceded to Republic of China Navy as Gu An in August 1947,
captured by PLAN and renamed Chang Bai in 1949, scrapped 1982
六連Hitachi-Sakurajima Shipyards25 July 194210 April 194331 July 1943Sunk by on 2 September 1943, Philippine Sea
壱岐Mitsui-Tamano Shipyards2 May 19425 February 194331 May 1943Sunk by on 24 May 1944, 150 miles W of Sarawak
対馬NKK-Tsurumi Shipyards20 June 194220 March 194328 July 1943Ceded to Republic of China Navy as Lin An 31 July 1947, scrapped 1963
若宮Mitsui-Tamano Shipyards16 July 194219 April 194310 August 1943Sunk by on 24 May 1944, East China Sea
平戸Hitachi-Sakurajima Shipyards2 November 194230 June 194328 September 1943Sunk by on 12 September 1944, South China Sea
福江Uraga Dock Company30 October 19422 April 194328 June 1943Ceded to UK in July 1947, scrapped
天草Hitachi-Sakurajima Shipyards5 April 194330 September 194320 November 1943Sunk by Royal Navy aircraft 9 August 1945, Onagawa, Japan
満珠Mitsui-Tamano Shipyards15 February 194331 July 194330 November 1943Scrapped 1946
干珠Uraga Dock Company8 April 19437 August 194330 October 1943Scuttled after mine damage, 15 August 1945, near Wonson, Korea
笠戸Uraga Dock Company10 August 19439 December 194327 February 1944Scrapped 1948